The chemical supercharging of racing engines has been used for some time in the racing and high performance vehicle industry for applying a sudden burst of power to the vehicle engine for increased engine horsepower and torque. One type of chemical supercharging is accomplished with nitrous oxide which is a chemical compound of nitrogen and oxygen commonly known as an oxidizer. Nitrous oxide when under sufficient pressure is in liquid form and when exposed to the heat of combustion in the engine it disassociates into its free elements of oxygen and nitrogen. When the nitrous oxide is injected into an internal combustion engine, it will create a very lean condition in the combustion chamber. This is alleviated by injecting additional fuel into the engine simultaneously with the nitrous oxide. When this is accomplished, the vehicle has an instant power gain and will deliver increased horsepower and torque to the engine. This will provide a sudden burst of power to the vehicle for use in the final stretch of a race or for passing another vehicle at a critical time in the race.
Nitrous oxide charging systems usually consist of a cylinder or container holding a supply of liquid nitrous oxide under pressure, for example approximately 900 psi. The nitrous oxide cylinder is connected by a conduit or supply line to the carburetor of the engine and has a solenoid actuated valve in the conduit for controlling the flow of the liquid nitrous oxide. The solenoid valve is operated by the driver from within the vehicle when the sudden burst of power is desired.
The nitrous oxide is maintained at this high pressure so that it will remain in a liquid state when it enters the carburetor to achieve the proper mixture of the oxygen, which is released by the nitrous oxide, with the fuel being supplied simultaneously to the carburetor through a fuel delivery line. The nitrous oxide cylinder is connected to a delivery solenoid by a section of conduit or tubing usually several feet long. This presents a problem in that the liquid nitrous oxide in the delivery conduit will vaporize before being injected into the vehicle engine upon actuation of the delivery solenoid by the vehicle driver. This results in an improper fuel mixture reducing the effectiveness of the fuel charging system. In order to eliminate this problem of the nitrous oxide vapors in the incoming line from entering the engine, a purge valve is actuated by the driver just prior to injecting the liquid nitrous oxide into the engine. This purge valve will vent the gaseous nitrous oxide in the delivery conduit into the atmosphere before energizing the delivery solenoid. Although this arrangement works relatively satisfactory, the gaseous nitrous oxide is vented to the surrounding atmosphere without any use being made of it. Also, the lower the temperature of the liquid nitrous oxide greater will be its density allowing more nitrous oxide to pass through the system for a given line pressure which provides for an increased boost of power when the liquid nitrous oxide is expanded to a gas in the vehicle engine.
Therefore, the need has existed for a device which precools and maintains the liquid nitrous oxide in the incoming delivery conduit at the lowest temperature possible to maintain the incoming nitrous oxide in liquid form prior to it being injected into the engine by actuation of the solenoid valve in the delivery conduit.